GRKs R4 self-countersinking screw has a patented underhead with saw-blade like patented cutting teeth and six self-contained cutting pockets. Together these features act like a circular saw blade, transporting the drill dust away from the edge of the screw hole while cutting a perfectly clean hole into even the most brittle materials without cracking any surface treatment. This design enhances the R4s versatility by allowing the fastener to countersink into even the hardest woods. The screw head closes the hole off with precision, not leaving any damaged fibers around the head.
